Router: TL-WR841N.    V13

Switch: TL-SF1005D.   V12

Pc1: ethernet connection 1219-V (probably broken) changed today with TL TG-3468  V3

Pc2: Qualcomm Atheros AR8151.

I had this config working fine for a year, but 2 weeks ago when I turned on the 2 pcs, internet was very slow compared to wi-fi, it was like 1 mbit ethernet and 10mbit wi-fi.

The next day ethernet stopped working with the message: ethernet doesn't have a valid ip configuration.

So I tried connecting the 2 pcs directly to the router and it was fine with the second, the first had another problem: a ethernet cable is not connected or is damaged, probably was the ethernet card because intel pro was like yo your switch is 255 meter distance and router 69km. 

After installing the new TL TG-3468 it works again connect directly.

but I need to connect the 2 pcs at the same time.

When connected to the switch, the router keep receiving DISCOVER from (Mac addres) 

And it send offer with IP 192.164.0.107 (es)

This continues indefinitely.

If I tried to connect only the 2 pcs with the router I can ping them. 

One more thing, when I change pc on the ethernet port or I connect the switch I need to restart my roter, i'm not sure it was like this before.

What do you think is the problem? After 2 week I'm a little tired of this situation.